Locking linkage for sofa bed



March 19, 'i957 Filed NOV. 20, 1953 J. S. PETERSEN LOCKING LINKAGE FOR SOFA BED gek March 19, 1957 J. s. PETERsEN 2,785,415

LOCKING LINKAGE FOR SOFA BED Filed NOV. 20, 1955 6 Sheets-Shea'l 2 jive/M752" W @v/gw@ 'y if Z f2.5 lm/alega March 19, 1957 J. s. PETERSEN LOCKING LINKAGE F'OR SOFA BED 6 she'ets-sheen a Filed Nov. 20, 1953.

March 19, 1957 J. s. PETERsl-:N 2,785,415

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LOCKING LINKAGE FOR SOFA BED Filed Nov. 20, 1953 6 Sheets-Sheet, 6

f 66 253 @jg 170 A mmff M@ 5 Dea/evz/ torsional strength. The side members of the seat section 55 are also preferably bent convex upwardly, as seen in the extended bed position of Figure l, so that when inverted in the seat position (Fig. 9) the side rails will bow downwardly and will not interfere with the resilient deflection of the seat cushions. The textile portion 63 of the mattress supporting fabric in the seat section is connected only to the cross rail of that section and to the adjacent edge of the wire link fabric in the adjoining intermediate section 51, no connection being provided to the side members of the frame so that the feel of the seat is equally as soft at the sides of the seating surface as it is in the center, and so that the seating surface will not hammock.

A mattress 67, preferably of innerspring construction, is supported upon the bed bottom, as shown in dotted outline in Figures l, 7 and 8.

The bed bottom is supported in the extended position by means of foldable legs 69 and 71 pivoted respectively to the outer section 55 and to the larger intermediate section 47, by means of a pair of links 73 each pivoted to the forwardly extending brace 39 of the stationary sofa frame and to a bracket 75 removably secured to the inner or head section 45 of the bottom, and also by means of curved arms 77 pivoted respectively to an angle bracket 79 secured to the side panel of the sofa frame, and to a bracket 81 secured to the intermediate section 47. The pair of links 73 and the curved arms 77 also serve to guide the folding movement of the bed bottom into the sofa frame, the pair of links 73 determining a fixed path of movement for the inner or head section 45 which, in turn, in conjunction with the curved arms 77, establishes a fixed path of movement for the intermediate section 47. The curved arms 77, one of which is provided at each side of the sofa bed, are connected by means of a torque tube 83 which assures their unison movement and thereby prevents racking of the foldable bed bottom as it is moved with respect to the stationary frame. The movement of the bed bottom into and out of the sofa frame is cushioned by means of tension springs 85, which are connected to the brackets S1 and to the front posts 27 of the sofa frame, and are stressed at both the fully folded and fully unfolded positions of the bed bottom to counterbalance a major portion of the weight of the bed bottom.

The folding of the bed bottom from the extended bed position of Figure l to the sofa forming position of Figure 9, occurs essentially in three stages. ln the first stage, the outer or seat section 55 is lifted and folded relative to the shorter intermediate section 51 about the hinge connection 57 between those two sections. '1" his folding action is limited to an approximately perpendicular relation between the two sections by means of a slotted linking link S7 which spans the hinge joint 57 and which is pivoted to the outer section at 39 and provided with an elongated slot 91 which encompasses a rivet 93 on the shorter intermediate section 51. At its end adjacent the pivotal connection of the link to the outer section, the slot 91 is provided with an offset 95, the outline of the slot being such as to cam the pin 93 into the offset 95 to limit the relative folding movement of the two sections. Thereafter, the outer section 55 and the short intermediate section 51, during continued folding movement, swing as a unit about the hinged connection between the two intermediate sections until the outer section 55 is inverted and overlies the larger intermediate section 47, lthis being the second stage of the folding operation.

Referring to Figure 7, which illustrates an intermediate position in the third and final stage of the folding action, it will be seen that when the outer section 55 is inverted, the locking link is urged by gravity to maintain the engagement of the pin 93 with the offset portion 95 of the slot, and that the offset portion of the slot is somewhat enlarged in the longitudinal direction of the link so as to provide a shoulder 97 disposedvat right Cir 4 angles to the long axis of the link for engaging the pin 93 (also Fig. S). Thus when the second stage of folding is completed, any unfolding of the outer section 55 and shorter intermediate section 51 relative to each other, due to the expansive force of the folded mattress, is limbythe engagement of the shoulder 97 with the pin 93.

The hinge joint 53 between the two intermediate sections 51 and d'7 is spanned by a bridging link 99 which is disposed on the inside of the hinge joint 53 and pivoted to the shorter intermediate section 51. At its other and, the .link 99 is provided with a pin 101 which engages elongated slot 103 in the larger intermediate section fr?. Thus, when the outer section 55 and the short intermediate section 51 are folded as a unit about the pivot 53, the pin 1M on the bridging link 99 moves rearwardly in the slot 195. lt will be apparent that any rearward force then exerted on the pin 101 will serve to further ff'ld the outer and shorter intermediate sections 55 and 51 about the pivot 5?, the latter two sections being locked together as a unit by the locking link 87.

This function is performed by an actuating link 105 which is pivoted at its rearward end at 107 to a bracket 1439 secured to the inner or head section 45 at a point beneath and spaced from the hinged connection 49 between the head section 45 and the large intermediate section 437 (Fig. l). At its forward end, the actuating link 165 is provided with an elongated slot 111, the lower edge of which extends generally parallel to the link axis, and the upper edge of which is in part also parallel to the link axis but in part offset so as to provide a hook or shoulder 113 for engaging the pin 101 on the bridging link 99 when the latter has been shifted rearwardly into the effective range of movement of the hook 113 during the second stage of folding movement, i. e., by the folding of the outer or seat section 55 into superposed relation with the large intermediate section 47.

During the third and final stage of folding movement, illustrated by Fig. 7, the inner section 45 and the larger intermediate section 47, with respect to which the outer and shorter intermediate sections 55 and 51 have been folded, move into the sofa frame, the head section being folded relative to the larger intermediate section during this movement, the path of which is completely determined by the pair of links '73 and by the curved arms 77. It will be noted by comparing Figs. l and 7, that the pivotal attachment of the actuating link 105 to the bracket 109 on the head section moves rearwardly relative to the pivotal connection 49 between the head and intermediate sections, thus drawing the actuating link rearwardly. Adjacent its hook-shaped slot 111, the actuating link 105 is provided with a cam slot 115 which engages a sidewardly projecting pin 117 on the larger intennediate section 47 of the bottom. The shape of the cam slot is such that as the actuating link is drawn rearwardly along the side of the intermediate section 47, it also moves downwardly relative to that section, bringing the hook or shoulder 113 into engagement with the pin 101 on the bridging link 99, and drawing the same rearwardly in the slot 163. This action of the actuating link, acting through the bridging link 99, the short intermediate Section 51, and the locking link S7, draws the seat section 55 downwardly against the expansive force of the folded mattress, and locks the same in fully folded condition relative to the larger intermediate section 47 as the bed bottom moves into the sofa-forming position of Fig. 9.

It will also be noted, comparing Figures 7 and 9, that the rearward movement of the actuating link relative to the intermediate section 4.17, is accompanied by upward movement of its rearward end as its pivotal connection 107 to the bracket 199 rotates rearwardly and upwardly about the pivot 49 between the two sections 45 and 47. Therefore, inasmuch as the actuating link becomes pivoted to the pin 1%31 on the bridging link 199 after the hook 113 and the pin 101 are engaged, it is necessary to provide a downwardly extending offset 1179, at the Outer avenant end of the cam slot A115 `to accommodate the upward swinging of the actauting link 105 about its disengageable connection to the pin 101.

A movable frontboard 121 is pivotally underslung from the outer section 55 adjacent its hinged connection to the short intermediate section 51. The frontboard (Fig. 3i) comprises a U-shaped angle iron frame 123, a wooden board 125 secured to the frame for receiving the upholstery material, and a pair of arms 127 rigidly secured to the .frame 1.23 and pivotally attached to the seat section at 129. The pivotal connection 1.29 of the movable frontboard structure 121 `to the seat section is spaced somewhat from the pivotal connection 57 of the seat section 55 to the short intermediate section 51, so that when 'these two sections are folded into essentially right angular relationship, and then further folded to bring the seat section into superposed relation with the larger intermediate section, the movable frontboard, which is disposed some distance beneath the mattress-supporting fabric in the extended position (Figs. l and 3) to prevent inter- `ference with deflection of the fabric, is folded snugly against the shorter intermediate section, the movable frontboard 121 being vertical in the fully folded position '(Fig. 9), at which it abuts the xed frontboard 43, cooperating with the latter to conceal the folded bed bottom.

The canvas portion 63 of the mattress-supporting fabric is provided, at the point of its connection, to the wire link portion 61, with an integral flap 131 which is connected to the movable frontboard 121, as shown in Fig. l. When the bed bottom is folded and in sofa-forming position, the ap 131 becomes taut and bridges the gap between the folded mattress fabric and the movable frontboard, to provide continuous front-to-rear support for the removable seat cushions.

The linkage for folding the support legs and the frontboard includes the links 133, 135 and 137. The link 133 for folding the outer leg 69 is pivoted to the movable frontboard frame 123 and to the` outer leg 69 at a point spaced below the pivotal connection of the outer leg to the seat section 55. The link 133 is also convex upwardly in the extended position so that when the parts are folded in the seat position, it, like the side member of the seat section 55, will be concave upwardly so as to preclude interference with the free deflection of the seat cushions. The folding of the outer leg 69 is limited by its engagement with an inwardly projecting pin 139 on the link 133, the folding of the leg being substantially lcompleted when the seat section 55 and the short intermediate section 51 are disposed in right angular relationship.

The outer leg 69 is provided with a post 141 which is secured to the leg at its upper end and extends generally radially from the xleg pivot and at right angles to the axis of the leg, lying in the plane of the seat section 55 when the leg is unfolded. However, when the leg 69 is folded into alignment with the seat section, the post 141 is disposed perpendicular-ly to the seat section, extending downwardly, when the seat section is inverted, to engage a pad or plate 143 carried by the actuating link 105, and thus to support the seat section 55 in the fully folded condition (Fig. 9).

In the folding of the seat section 55 relative to the short intermediate section 51, the movable frontboard 121 is also raised, and as the seat `section and short intermediate section are folded in unison about the pivot 53, the frontboard approaches the short intermediate section 51, its folding movement being also controlled by the link 135, which is pivoted to the frontboard frame 123, and to the intermediate support leg 71. The link 137 for folding the intermediate support leg '71 is pivoted to the leg on la `common pivot with the link 135 and is pivoted at its rearward end to the bracket 109 'secured to the head section 45, 4on -a common pivot 107 with the actuating link 105. Thus, as the last mentioned pivot point moves rearwardly relative to 'the intermediate `section during the relative `folding of the Ahead section 4S and large intermediate section 47, which occurs 'during the `final folding action, the intermediate support leg 71 folded against the underside of the large intermediate section d'7 (Fig. 7), and the link 135 draws the lower end of the frontboard 121 inwardly toward the intermediate section 51.

The sofa `bed structure as thus far described `is shown in part in Patent 2,333,087, which discloses the connection of the bed bottom to the stationary sofa frame, lin Patent 2,352,989 which discloses the particular arrangementof the bed bottom fabric, in 4Patent 2,595,038 and my copending application Ser. No. 302,870, now Patent No. 2,749,559, granted June 12, 1956, which disclose the locking linkage as thus far described, and in the co-pending application of Edward E. Woller, Ser. No. 79,131 filed March 2, 1949, which discloses and claims the L-shaped outer leg 69 and other features hereinbefore described but not part of my invention.

AThe present improvement is particularly concerned with the action of the slotted locking link S7 which spans the hinge joint 57 between the seat section 55 and the short intermediate section 51. In the form of locking linkage `disclosed in Patent 2,595,038 and in my co-pending application Ser. No. 302,870, now Patent No. 2,749,559,

granted lune 12, 1956, previously referred to, the operation of the slotted locking link 87 depended upon the force of gravity to disengage itself from the pin 93 during the unfolding of the bed bottom. Referring, for example, to Figures 7 and l, it will be apparent that as the seat section 55 is moved from its folded, superposed position to its extended position, and vice versa, the link 87 is inverted; thus, Whereas in the folded position (Fig. 7), the offset 95 of the slot 91 extends upwardly, in the fully extended position (Figs. l and 3) it extends downwardly, and the direction of the force of gravity is such Ias to unseat the pin 93 from the offset 95 as the seat sec tion -55 and short intermediate section 51 are unfolded as a unit about the pivot 53, i. e., unfolded from the superposed relation indicated by Figure 7 (but with the head section and larger intermediate section 47 co-planarly aligned) to the position of Figure 6. However, if as sometimes occurs in the manufacture, the locking link 87 is riveted `too tightly to the outer section at the pivot 89, the link does not fall freely of its own Weight, and it is not possible to `unfold the seat section 55 relative to the shorter intermediate ysection 51 beyond the right angular position of Figure 6 without manually disengaging the pin 93 from the offset 95. rThe difficulty is not encountered in the folding action because the outer radius of the juncture of the longitudinal slot 91 with its olfset is such as to positively cam the pin 93 into the offset 95 against whatever resistance may be oifered by excessive friction in the pivot point 89 between the locking link and the seat section.

The improvement consists in provi-ding a slotted |control link 145 for positively unseating the pin 93 from the offset 95 as an incident of the unfolding of the seat sectio-n 55 and intermediate section 51 as a unit about the pivot 53. The control link 145, and its action during the iinal portion of the unfolding movement just described, is shown in detail in Figures 3 to 6, inclusive.

The control link 145 is pivoted at one end to the frontboard frame 123 on a common pivot with the link 135 which is connected between the frontboard and the intermediate support leg 71. At its other end the link is provided with a slot 147 which encompasses a pin 149 secured to the locking link 87. Referring in order to Figures 4, 5 and 6, which demonstrate the action of the link in unseating the pin from the offset, Figure 4 `shows the seat section 55 and the short intermediate section 51 just before the completion of their unfolding movement as a unit about the pivot 53 between two intermediate sections (note that the bridging link 99 which spans the hinge joint 53 is still disposed at an angle t-o the short intermediate section 51), In this position, the control link 145 which, during the unfolding movement, is being drawn downwardly by the descending frontboard 121, is disposed with the outward end of its slot 147 just engaging the pin 149 `on the locking link 87.

In Figure 5, the unfolding movement of the sections 55 and 51 about the pivot 53 is completed, as indicated by the parallelism of the bridging link 99 and the short intermediate section 51, during which further unfolding movement the slotted control link 145 moves the locking link 87 downwardly about its pivot 39, positively unseating the pin 93 from the offset 95 against whatever resistance may be offered by friction at the pivot 89.

Figure 6 shows the intermediate section 51 fully unfolded relative to the larger intermediate section 47, and with the unfolding of the seat section S relative to the short intermediate section 51 proceeding. During this last unfolding movement, the locking link S7 is carried forwardly by the seat section, and the pin 93 moves rearwardly in the slot 91. At the same time, the pin 149 moves downwardly in the slot 147 of the control link 145 to assume the position shown in Figure 3 when the bed bottom is completely unfolded `to the bed position.

In the embodiment of Figures 1 to 9 inclusive, the entire effective action of the control link 148 occurs between the positions of Figures 4 and 5.

in the embodiment of Figures to 15 inclusive, the construction and operation of the sofa bed is substantially identical with that already described in connection with Figures l to 9 inclusive, the modifications being those incident to the incorporation of a bed bottom into a sofa frame of greater width. The differences are most readily apparent from Figure 11, which shows that the double suspension links 154i, corresponding to the suspension links '73 of the embodiment of Figures 1 to 9, and the mounting arm 152, corresponding to the mounting arm 77 of the embodiment of Figures l to 9, are bent or offset to bridge the gap between the bed bottom 154 and the side panels of the stationary sofa frame 156. The other differences are centered at the juncture of the seat section 158 with the shorter intermediate section 16d, the seat section being necessarily wider than in the embodiment of Figures 1 to 9, in order to provide a continuous seating surface from side to side of the sofa within the sofa arms. Being located near the joint 162 between the seat section 152i and short intermediate section 160, modication of the control link is also necessitated, as will shortly be described.

Because of the difference in widths of the seat section 158 and the intermediate section 16), the seat section is pivoted to an angle-shaped hinge bracket 164 which is secured to and projects sidewardly from the intermediate section 160. A slotted locking link 166, corresponding to the similar locking link 87 of Figures 1 to 9, is pivoted at 163 to the inside of the side member of the seat section and engages a pin 17d projecting outwardly from the side member of the short intermediate section 160. As best seen in Figure 12, the hinge bracket 164 and the side member of the seat section 158 partialiy overlie the slot 1722 in the locking link 166, necessitating that the slotted control link 174 be connected to the locking link 166 by means of a pin 176 secured to the locking link on the side of the slot 172 opposite that to which the corresponding pin 149 of Figures 1 to 9 is secured, i. e.,

opposite the offset portion of the slot. The difference in width between the seat section and short intermediate section, and between the frontboard and the short intermediate section also necessitates that the ends of the control link '174 and the frontboard folding link 17S be offset, as best seen in Figure 1l.

The mode of operation of the modification of Figures 10 to l5 inclusive is, however, the same as that of Figure 9, as wiil be apparent from inspection of Figures 13, 14 and l5 in order, which show the modified construction in the same stages of unfolding as do Figs. 4 to 6 inclusive the previously described embodiment.

Figure i3 illustrates the beginning of the final stage of the unfoiding movement of the seat section 158 and the short intermediate section 16@ as a unit abount the pivot between the two intermediate sections, 166 and 132, as indicated by the angularity of the bridging link 184 with respect to the short intermediate section 160. In this position the outer end of the slot 186 of the control link 174 is just engaged with its associated pin 176, and the pin associated with the locking link 166 remains in the offset portion of the slot.

Figure 14 shows the same parts unfolded to a slightly greater degree, i. e., with the unfolding of the seat section .iii-Sti and short intermediate section 16d about the large recate section 182 completed. ln the slight change rom Figure 13 to Figure 14, the movement of the short ntermediate section 16@ (and the locking link 166) relative to the frontboard, which is guided by the link 178, tensions the siotted control link 174 and exerts a force on the pin 176 which rotates the slotted locking link 166 in a direction to unseat the locking pin 17d from the offset of the slot 172 against whatever resistance might be offered by friction between the relatively movabie parts, particulariy at the pivot 168.

Figure 'l5 illustrates the relationship of the parts when relative unfolding between the two intermediate sections is complete and relative unfolding of the seat and the short intermediate section has just begun. In this last stage of unfolding, the slotted locking link 166 is carried forward, which has the effect of moving the pin 170 rearwardiy in the slot 172. At the same time, the frontboard drops farther away from the bed bottom until, when the bed bottom is completely unfolded, the parts assume the positions shown in Figure 12. As is the case with the embodiments of Figures 1 to 9, the effective action of the control link 174 takes place between the positions of Figures 13 and 14.

Buring the foiding movement of the bed bottom, the progression of successive relationships of parts is the same as that illustrated by Figures 4 to 6 inclusive for the first embodiment, and Figures 13 to l5 inclusive for the second embodiment, considered inthe reverse order. During the foiding movement, considering the embodiment of Figures 1 to 9 inclusive as illustrative, the locking pin 93 moves toward the offset end of the slot 91, reaching the beginning of the curved portion of the slot edge as the end of the slot 147 of the control link 145 engages the pin 1.49 on the locking link. However, as the folding progresses and the frontboard is raised, the control link 145 releases the pin 149 whereupon, the locking pin 93 is seated in the offset by the camming action of the curved juncture of the longitudinal portion of the slot 91 with its offset 95, as the folding of the outer or seat section and the intermediate section, Fig. 5 being illustrative of the relationship of the parts just prior to the seating of the pin 93 in the offset 95.

in the foregoing, there has been described an improved locking linkage for sofa beds of the indicated type which is positive in its operation in both the folding and unfolding movements of the bed bottom, and therefore not susceptible to improper or faulty operation as a result of uncontrollable irregularities of manufacture or assembly. Features of the invention believed to be new and patentable are set forth in the appended claims.

I claim:

1. A folding bed bottom for sofa beds comprising a plurality of hingedly connected bed bottom sections including an outer end section, a second section hinged to said end section and a third section hinged to said second section, said sections being relatively foldable from coplanar alignment to dispose said end section in overlying relation to said third section and spaced therefrom by said second section, mounting means connected to said third section for movably mounting said bed bottom on assassin a sofa frame to extend forwardly therefrom in co-planar bed position and to be movable rearwardly, when folded as aforesaid, into said sofa frame to form the sofa seat, a link connected between said end section and said second section and being pivoted to one of them and having a slot engaging a pin on the other, said slot having an offset at the end thereof adjacent the link pivot, said slot and offset being curved at their juncture to provide a cam surface for forcing said pin into said offset to limit relative folding of said end and second sections, said link, when said pin is disposed in said offset and when said end section overlies said third section as aforesaid, locking said end and second sections together thereby to prevent relative unfolding of said two sections, means connected between said mounting means and said second section and actuated by the rearward movement of said folded sections into said seat position on the sofa frame to lock said second section against unfolding movement relative to said third section, and to unlock said second section by forward movement of said folded sections from said seat position, and linkage means connected between said third section and said slotted link for disengaging said pin and said offset when said end and second section are unfolded relative to said third section, thereby to permit the unfolding of said end section relative to said second section to place said sections in co-planar bed position.

2. A folding bed bottom for sofa beds comprising a plurality of hingedly connected bed bottom sections including an outer end section, a second section hinged to said end section and a third section hinged to said second section, said sections being relatively foldable from coplanar alignment to dispose said end section in overlying relation to said third section and spaced therefrom by said second section, a link connected between said end section and said second section and being pivoted to one of them and having a slot engaging a pin on the other, said slot having an offset at the end thereof adjacent the link pivot, said slot and offset being curved at their juncture to provide a cam surface for forcing said pin into said offset to limit relative folding of said end and second sections, said link, when said pin is disposed in said offset and when said end section overlies said third section as aforesaid, locking said end and second sections together thereby to prevent relative unfolding of said two sections, and linkage means connected between said third section and said slotted link for disengaging said pin and said offset when said end and second sections are unfolded relative to said third section, thereby to permit the unfolding of said end section relative to said second section to place said sections in co-planar bed position.

3. A sofa bed comprising a normally stationary sofa frame, a foldable bed bottom including an outer end section, a second section hinged to said end section, and a third section hinged to said second section, said sections being foldable from co-planar bed alignment to dispose said end section in overlying relation to said third section and spaced therefrom by said second section, mounting means movably supporting said bed bottom on said frame whereby said sections when folded are movable inwardly of said frame to form a sofa seat, a locking link connected between said end and said second sections and being pivoted to one of them and having a slot engaging a pin on the other, said slot having an offset at the end thereof adjacent the link pivot, said slot and offset being curved at their juncture to provide a cam surface for forcing said pin into said offset to limit relative folding of said end and said second sections, said locking link, when said pin is disposed in said offset and when said end section overlies said third section, locking said end and said second sections together to prevent. relative unfolding thereof, a toggle linkage connected between said end section and said third section, and a link connected t0 said toggle and having a lost motion connection to said slotted locking link, said toggle and connecting link being effective to disengage said pin and said offset during the unfolding of said end and said second sections relative to said third section, thereby to permit the unfolding of said end section relative to said second section to place said sections in co-planar position.

4. A sofa bed comprising a normally stationary sofa frame, a foldable bed bottom including an outer end section, a second section hinged to said end section, and a third section hinged to said second section, said sections being foldable from co-planar bed alignment to dispose said end section in overlying relation to said third section and spaced therefrom by said second section, mounting means movably supporting said bed bottom on said frame whereby said sections when folded are movable from a position outside of said frame inwardly of said frame to form a sofa seat, a locking link connected between said end and said second sections and being pivoted to one of them and having a slot engaging a pin on the other, said slot having an offset at the end thereof adjacent the link pivot, said slot and offset being curved at their juncture to provide a cam surface for forcing said pin into said offset to limit relative folding of said end and said second sections, said locking link, when said pin is disposed in said olset and when said end section overlies said third section, locking said end and said second sections together to prevent relative unfolding thereof, a foldable leg pivoted to said third section for supporting said bed bottom in said outside position, link means connected between said leg and said mounting means for folding said leg when said bed bottom is moved inwardly to seat position, a frontboard pivotally connected to said end section for concealing said bed bottom in folded sofa seat position, a link connected to said leg and to said frontboard for swinging said frontboard away from said bed bottom when said sections are unfolded, and a control link connected to said frontboard and having therein a slot encompassing a pin on said locking link, said control link engaging the pin on said locking link during the unfolding of said end and second sections relative to said third section, to disengage the rst mentioned pin and the odset in said locking link, thereby to permit the unfolding of said end section relative to said second section to place said sections in co-planar alignment.

References Cited in the le of this patent UNITED STATES PATENTS 3,192,137 Svebilius July 25, 1916 1,379,805 Dewey May 31, 1921 2,595,038 Woller April 29, 1952 

